Linking Restoration and Ecological Succession (Springer ... - Inecol

Chapter 2 Insights Gained from Succession for the Restoration of Landscape Structure and Function 21
to restoration. Unfortunately, high productivity often only favors competitive
species that produce dense vegetation and arrest structural development and
limit biodiversity. Thus, restoration programs in relatively fertile sites, where
the priority is to attain high biodiversity quickly, may fail unless fertility is
limited and monitored.
2.1.3 Succession and Responses to Environmental Impacts
Succession is the process of species replacements accompanied by ecosystem
development. Disturbances cause abrupt changes in or losses of biomass, usually
associated with similar changes in ecosystem function. Succession occurs
after disturbances that range from mild to severe. Mild disturbances, such as
infrequent light ground fire regimes in fire-tolerant vegetation, do little damage.
While relative proportions of species change following mild disturbances,
species turnover is not directional. Nutrients may be lost and many individuals
die, but most species survive. This process of recovery is sometimes called
regeneration dynamics, not succession. It is uncommon that restoration will be
required in such cases, unless diversity enhancement is required to overcome
the consequences of overgrazing or intense fires.
Secondary succession occurs after more severe disturbances such as canopy
fire (Beyers 2004) and flooding. Common anthropogenic examples include recovery
when farming or grazing cease (Bakker and van Wieren 1998). A legacy
of species may persist, but often it consists of undesirable nontarget species.
Achieving structure and function comparable to developed vegetation may take
decades if the only species that persist are those adapted to disturbances. In
these cases, restoration can establish more complex, efficient ecosystems by
early, targeted species introductions.
Primary succession occurs after severe disturbances that form new surfaces.
Rarely is there a biological legacy, so regeneration is driven from outside the
site. Familiar natural examples include lavas, surfaces revealed by retreating
glaciers, landslides, and floods (Walker and del Moral 2003). The trajectory of
development is unpredictable because the lack of survivors leaves a blank slate
upon which many alternatives might be established.
The predictability of restoration can be improved by introducing species
expected to form the fundamental structure of the desired system (Turner et al.
1998). Definitive model communities for restoration (“nature target types”)
exist for The Netherlands (Bakker 2005), and could be developed for other
regions from available descriptions of plant communities (Rodwell 1991–2000,
Schaminée 1995–1999, Wolters et al. 2005). Choosing a model community, or
suite of communities, depends on the historical context of the target. Restoring
rural landscapes to include examples of meadows under moderate grazing, for
example, requires data from 19th century descriptions (Bignal and McCracken
1996). However, we emphasize that restoration for biodiversity conservation
should aim at multiple targets and a mosaic of habitats. In some cases, no
target or model community is known in detail, so target communities must be
improvised.
2.1.4 Structure and Function
If an ecosystem has suffered only minor disturbance, structure and function may
develop together. Few of the missing elements require immediate replacement